This invention relates generally to DC-to-DC. converters and more particularly to a pulse-width modulated switching converter.
DC-to-DC power converters utilizing a switching device in a combination of inductors and capacitors to derive power from one source of DC voltage and then deliver that power to a load at the same or a different DC voltage are well known. Many different types of topologies exist for implementing such power converters. The number of different possible combinations using but a relatively few components has resulted in several standard topology types which include, among others, the buck, boost, buck-boost, forward, flyback, and CUK converters. With what initially appears to be only a simple change or a modification in the particular converter implementation, an extremely significant performance variation can result.
While many different topologies could be described, each with its own advantages and disadvantages, the configurations shown in FIGS. 1-3 best represent prior art topologies which exhibit the closest similarity to that of the subject invention to be hereinafter described.
FIG. 1, for example, discloses what might be termed a forward converter topology and comprises an isolated or transformer version of a buck converter which, without an input filter, is typically characterized by a converter which displays discontinuous input current while providing a continuous output current. Such an arrangement offers an efficient power conversion technique; however, it almost always requires the use of a reset winding on the power transformer in order to reset the transformer core by returning its stored energy to the primary side. This requirement, while not being difficult to implement, creates some additional design considerations associated with the reset circuitry.
With respect to the circuitry shown in FIG. 2, it exemplifies what is termed flyback converter topology and comprise what might be referred to as an isolated or transformer version of a boost converter which, without an input filter, is characterized by discontinuous input current while also providing discontinuous output current and where the required inductor is incorporated into the transformer which comprises a flyback transformer. It typically offers the smallest number of components for DC-to-DC power conversion.
The third configuration comprises topology which is illustrative of an isolated or transformer version of the CUK converter. An isolated CUK converter utilizes a transformer which is capacitively coupled both on the primary and secondary sides.
While each of the above-referenced power converters as well as other known converter topologies have known utility, inherent limitations and certain disadvantages nevertheless exist.